Question

Calculate the concentration of each standard in terms of ppm iron. FW= 55.845 g/mol. Please show your work. First prepare standard solution from a standard Fe stock of 0.13 M. Make 100x dilution (1 mL of stock into 100 mL of water) Then, using a pipet deliver the following volumes of your Fe standard diluted solution into 10 mL volumetric flasks: 0 microliters, 150 micro liters, 300 microliters, 450 microliters, and 600 microliters.

Answer 1

Concentration of each standard in terms of ppm of iron is calculated as follows:

Answer 2

Given:

• Stock Fe solution concentration: 0.13 M

• Dilution: 1 mL stock → 100 mL (100x dilution)

• Final volumes: 10 mL (in volumetric flasks)

• Volumes of diluted standard added: 0 µL, 150 µL, 300 µL, 450 µL, 600 µL

• Molar mass of Fe (FW): 55.845 g/mol

• 
  

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Step 1: Prepare the Diluted Standard Solution

1. Diluted Fe concentration (100x dilution):

   $${\text{M}}_{\text{diluted}}=\frac{0.13\text{M}}{100}=0.0013\text{M}$$

2. Convert to ppm (mg/L):

   $$\text{ppm}=\text{M}\times \text{FW}\times 1000=0.0013\times 55.845\times 1000=72.60\text{ppm}$$

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Step 2: Calculate Fe Concentration in Each 10 mL Flask

General Formula:

$${\text{C}}_{\text{final}}=\left(\frac{{\text{V}}_{\text{added}}(\text{µ}L)}{10,000\text{µ}L}\right)\times 72.60\text{ppm}$$

(Since 10 mL = 10,000 µL)

Volume Added (µL)	Calculation	Final Concentration (ppm Fe)
0	$0$	0.00
150	$(150\mathrm{/}10,000)\times 72.60$	1.09
300	$(300\mathrm{/}10,000)\times 72.60$	2.18
450	$(450\mathrm{/}10,000)\times 72.60$	3.27
600	$(600\mathrm{/}10,000)\times 72.60$	4.36

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Answer:

Standard	Fe Concentration (ppm)
Blank	0.00
150 µL	1.09
300 µL	2.18
450 µL	3.27
600 µL	4.36